It looks to me as though the room being described is in fact one enormous wind-chest. I think the pallets (beneath the pipes to admit air when required) are in the roof. This is an interesting arrangement indeed.

Edit: a bit of googling has shown this to be the 'Universal Windchest' invented by Austin:

I briefly played the Curtiss in 1991 while attending my sons graduation at the University of Pennsylvania and I remember two large walk in windchests the size of highway shipping containers suspended above the left and right mezzanine seating areas. Cannot recall if the windchests to the left and right of the proscenium stage and in the rear mezzanine were walk in chests?